Process for producing high viscosity wax oxidate



PROCESS FOR PRODUCING HIGH VISCOSITY WAX OXIDATE No Drawing. ApplicationOctober 26, 1950, Serial No. 192,382

4 Claims. (Cl. 260-451) This invention relates to a method for oxidizinghigh molecular weight paratfins so as to produce a high ester content,high viscosity oxidate. This type of oxidate is an excellent additivefor mineral oil to produce specialty lubricants.

Oxidation of high molecular weight hydrocarbons with air or oxygenresults in the production of a heterogeneous mixture of oxygenatedcompounds. Not only are many different types of oxygenated hydrocarbonsproduced, .but oxygenates of a Wide molecular weight range resultbecause the oxidation is accompanied by substantial chain degradationeven when a relatively close boiling charge material is employed. Thecomplexity of the oxidation product is apparent from a brief review ofthe types of oxygenates obtained. Acids, alcohols, aldehydes and ketonesare all produced directly in the oxidation reaction. Acids are the mainreaction product, with hydroxy hydrocarbons constituting the secondlargest product. Further oxidation of the acidsleads to the productionof hydroxy acids and keto acids. In addition, at the oxidationtemperatures ordinarily employed, which are in the range of 200 to 400F., a number of secondary reaction products are formed; in particular,there is a substantial amount of thermal estcrification of organic acidswith hydroxy acids and with alcoholic components of the reactionmixture.

Despite the extensive nature of the prior art on Wax oxidation, both thetechnical and patent literature are deficient in teaching how to controlthe oxidation reaction so as to produce a product oxidate characterizedby both high ester content and high viscosity. The prior art doesdisclose that a relatively high ester content oxidate is normallyproduced in the oxidation reaction but is devoid of any teaching how theviscosity of the high ester content oxidate can be controlled asdesired. The

subject application provides a method for producing a high ester contentoxidate in which the Saybolt Univ. viscosity at a temperature of 210 F.is higher than 4000. Eight ester content, high viscosity wax oxidate isuseful as a lubricating oil additive to impart corrosion resistance andemulsibility and possesses exceptional and surprising solubility inlubricating oil fractions.

In accordance with the process of this invention, a Wax oxidate of highester content and high viscosity is obtained by reacting high molecularweight hydrocarbons of the class comprising petrolaturn and lubricatingoil fractions with air in the presence of a catalyst at an air feed rateof 15 to 35 standard cubic feet of air per pound of hydrocarbon perhour, at a temperature between 270 and 400 F. and at atmosphericpressure. The critical features are choice of charge material, use ofcatalyst, maintenance of prescribed temperature and pressure conditions,and use of' an air rate within the prescribed region. Employing theprescribed conditions, a product oxidate having a ratio of Neut. No. toSap. No. less than about 0.25 and a Saybolt Univ. viscosity at 210 F.greater than 4000 is obtained by oxidation of a petrolatum. Even whenthe charge material is a viscous lubricating oil fraction, an oxidatehaving a Saybolt Univ. viscosity at 210 F. greater than 1500 is obtainedemploying the oxidation conditions prescribed in this invention.

The subject invention in contrast with prior art processes affords ameans of producing oxidates whose'ester content is approximately 2 timesits acid content, as indicated by a ratio of Neut. No. to Sap. No. lessthan 0.40, and which have a Saybolt Univ. viscosity at 210 nitcd StatesPatent 2,705,241 Patented Mar. 29, 1955 ice F. between 1500 and 11,000.In general petrolatums oxidized under the prescribed conditions yieldoxidates Whose ratio of Neut. No. to Sap. No. is less than 0.25 whilelubricating oils'yield oxidates whose ratio of Neut. .No. to Sap. No. isless than 0.40. In addition, the product of the aforementionedcharacteristics is obtained in a short reaction time under theprescribed reaction conditions.

The discovery that the viscosity of a high ester content oxidate can becontrolled as desired by selection of charge stock, use of catalyst andcritical control of temperature, pressure and air rate is a significantadvance in the field of waxoxidation. The process of this inventionresults in the formation of a high viscosity, high ester content oxidatewhich is an excellent additive for lubricant compositions whereinanti-corrosive properties in combination with good water emulsificationare required specifications; The high ester content, high viscosityoxidatc produced in accordance with this invention is an excellentadditive for marine oil to which it imparts desired anti-corrosive andemulsibility'properties.

The selection of charge material has a significant and substantialeffect on the type of oxidate produced. Petrolatums and lubricating oilfractions are the requisite charge materials to produce high estercontent, high viscosity oxidate. Petrolatum is obtained by the solventdewaxing of residual oils. It is not feasible to prepare high estercontent oxidate having SUS viscosities'well over 1500 at 210 F. fromdeoiled waxes. With petrolatum as a charge stock it ispossible toproduce. high ester content oxidates-Whose Saybolt Univ. viscosity at210 F. is higher than 6000.

In general, the production of high ester content, high viscosity oxidateis effected in an aluminum-lined reactor in the presence of a catalyst.Particularly preferred catalyst. is potassium permanganate which .ischarged to the reactor in an aqueous solution together with petrolatum.A potassium permanganate catalyst of this nature is employed in amountsranging from 0.01 to 1.0 per cent of the total Wax charge; 3 to 10 percent aqueous solutions of potassium permanganate are ordi narily used tointroduce the required catalyst into the reaction zone. Excellentdistribution of the potassium permanganate throughout the hydrocarboncharge is obtained in the induction period during which air is blownthrough the reaction mixture and the reaction mixture is raised to thespecified temperature range. The water evaporates during the inductionperiod, leaving the catalyst distributed throughout the charge veryuniformly. Although potassium permanganate in the form of an aqueoussolution is the preferred oxidation catalyst, oil.- soluble catalystssuch as manganese stearate, zinc stearate, manganese and zinc salts ofpreviously oxidized wax fractions may also be employed in the process ofthis invention to produce a high ester content, high viscosity oxidate.a

The oxidation temperature must be maintained between 270 and 400 F. inorder to produce a high ester content,.high viscosity oxidate. Thepreferred temperature range is 300 to 380 F. Control of reactiontemperature is ordinarily eifected by indirect heat exchange. Analternative means of temperature control involves continuousintroduction of water into the reactionzone, which results in removal ofexothermic heat of reaction by evaporative cooling.

Atmospheric or sub-atmospheric pressure is prescribed to produce a highester content, high viscosity oxidate. It is important to maintainpressures below about 20 pounds per square inch gauge in the process ofthis invention because higher pressures result in the production of amore acid-like oxldate.

The final decisive factor in the process of this invention is the rateat which air is passed through the oxidate. Air rates of 15 to 35standard cubic feet of air per pound of petrolatum per hour must beemployed to obtain the desired product. The air rate is particularlydecisive in determining the viscosity of the highester content oxidate.vApparently air rates of the. prescribed range result in the propercorrelation of agitation and contact of reactants to produce a'hiighester content, high viscosity oxidate at the prescribed temperature andpres sure conditions. It should be noted that the amount of air passedthrough the reaction mixture is considerably in excess of that whichactually enters into the oxidation reaction.

The process of the invention is illustrated in detail in the followingexamples wherein petrolatum and lubricating oil fractions are oxidizedin accordance with the process of this invention. Examples I and IIillustrate the production of high ester content, high viscosity oxidatesfrom petrolaturn, whereas Examples III and IV illustrate the preparationof high ester content, high viscosity oxidates from lubricating oilfractions.

Example I There was charged to an aluminum reactor provided with heatexchange surface 150 pounds of petrolatum obtained by centrifugedewaxing of a refined residuum; the charge petrolaturn-had the followingproperties:

Gravity, API 20.5 Flash, 0. Cleve., F 520 Fire,'C1eve., F 590 Visc.,Say. Univ., at 210 F; 86.6 Color, T. R 1/ 4 Melting point, F 151.8 Ash,per cent .008 Sulfur, per cent .19

Oil, per centtASTM) 13.39

dation was effected at atmospheric pressure. and at an air rate of 20cubic feet of air per pound of petrolatum per hour. The reaction wascontinued at these conditions for a period of about 6% hours, at whichtime the oxidate had reached a Neut. No. of 26 and a Sap. No. of 126.There was obtained a yield of approximately 86 per cent oxidate on thebasis of hydrocarbon charged. The product'obtained had'a Saybolt Univ.viscosity at 210'F.' of 6211 and was characterized by the followingtests:

Neut. No Sap. N 126 Ester No 100 Ratio Neut. ,No./ Sap. N0 0.21Unsaponifiable, per cent 37.3 Gravity, 'API 17.3 Flash, 0. Cleve, F 475Fire, Cleve, F 510 Visc. SU, 210 F 6211 Pet. melting point, F 142 Ash,per cent 0.56

1 Example II 100 pounds of petrolatum of the type described in Example lwas charged to an. aluminum reactor. There was also charged to thereactor an'aqueous solution of potassium permanganate prepared bydissolving 0.4 pound of potassium permanganate in 10 pounds of water.After the induction period, the reaction was effected for a period ofabout hours at an average reaction tern perature of 360 F. and atatmospheric pressure; the air rate was 30 cubic feet of air per pound ofpetrolatum per hour. The yield of oxidate was approximately 96 .per centof the hydrocarbon charged.- The product oxidate had a Saybolt Univ.viscosity at 210 F. over 11,000 and was characterized by the followingproperties:

Neut. No 2.3 Sap. No 65 Ester No 62 Ratio, Neut. No./ Sap. No .05Unsaponifiabie, per cent 32 Gravity, API 17.6 Flash, 0. Cleve, F 495Fire, Cleve, F 550 Visc., Say. Univ., at 210 F 11,038 Ash, per cent Y.61

Neut. No

Gravity, API 31 Flash, 0. Cleve., F 295 Fire, Cleve, F i. 335 Visc.,Say. Univ., at 100 F 48 7 Pour, 'F., maximum -75 Viscosity index,minimum; 60

There wasalso charged to the reactor an aqueous solution prepared bydissolving 0.4 pound of potassium permanganate in 10 pounds of water.'The oxidation procedure was the same as that described in Example I;the reaction was effected at a temperature of 330 F., at atmosphericpressure and at an air rate of cubic feet of air per pound of charge oilper hour. At the end of 5 /5 hours there was obtained an 'oxidate having2. Saybolt Univ. viscosity at 210 F. of 1631. The product oxidate wascharacterized by'the following tests:

7 82 Sap. No 222 Ester No 140 Ratio, Neut. No./Sap. No 0.37Unsaponifiable, per cent 32.3 Gravity, API 3.2 Flash, 0. Cleve, F 320Fire, Cleve.,. F 410 Visc., Say. Univ., at 210 F 1631 Color, /2" Lovi.Cell 85 Example IV In. an'aluminum reactor provided with heat exchangesurface a lubricating oil fraction having been obtained by solventdewaxing paraffin distillate 40 was oxidized in accordance withtheprocedure describedin Example I. The charge oil had the followingproperties:

Gravity, API 27.3 Flash, 0. Cleve, F 495 Fire, Cleve, F 560 Visc., Say.Univ., at 210 F 77.2 Visc., Say. Univ., at F 824 Color, Lovi. /2" Cell40 Four, F -5 Neut. NO 34 Sap. N0 Ester No '76 Ratio, Neut. No./Sap. No0.31. Unsaponifiabie, per cent 41.5 Grav'ity,' API 10.2 Vis., SU, 210 F1 2515 Pour, F 95 It will be observed that oxidation of petrolatum andmineral oils in accordance with the process of this in higher than 6000and are characterized by a ratio of Neut. No. to Sap. No. less thanabout .25. The oxidates produced by oxidation of mineral oils have aSaybolt Univ. viscosity at 210 F. higher than 1600 and are char--Scierized by a ratio of Neut. No. to Sap. No. less than The oxidatesproduced in accordance with the process V of this invention possessexcellent solubility in lubricating 7 oil fractions and are excellentadditives for imparting emulsibility and corrosion resistance to thelubricating fractions in which they are incorporated.

Obviously, many modifications and variations of the invention ashereinbefore set forth may be made without departing from the spirit andscope thereof and, therefore, only such limitations should be imposed asare indicated in the appended claims.

We claim: 1. A wax oxidate derived by the catalytic liquid phaseoxidation of petrolatum at a temperature between 270 and 400 F., at apressure below 20 pounds per square inch gauge and at an air feed rateof 15 to 35 cubic feet of air per pound of petrolatum per hour, saidoxidate being characterized by a Neut. No. to Sap. No. ratio lesstha(r)100.25 and a Saybolt viscosity at 210 F. greater than 2. A processfor producing a high viscosity, high ester content petrolatum oxidatecharacterized by a Neut. No. to Sap. No. ratio less than 0.25 and an SUVat 210 F. greater than 4,000, which comprises reacting petrolatum withair in the presence of a catalyst at a temperature between 270 and 400F., at a pressure below 20 p. s. i. g. and at an air rate between 15 and35 cubic feet of air per pound of petrolatum per hour.

References Cited in the file of this patent UNITED STATES PATENTS2,156,266 Murphree et a1 May 2, 1939 2,168,699 Burk Aug. 8, 19392,216,222 Beller Oct. 1, 1940 2,486,454 Zellner Nov. 1, 1949 2,542,697Nevison et a1. Feb. 20, 1951 potassium permanganate con-

1. A WAX OXIDATE DERIVED BY THE CATALYTIC LIQUID PHASE OXIDATION OFPETROLATUM AT A TEMPERATURE BETWEEN 270 AND 400*F., AT A PRESSURE BELOW20 POUNDS PER SQUARE INCH GAUGE AND AT AN AIR FEED RATE OF 15 TO 35CUBIC FEET OF AIR PER POUND OF PETROLATUM PER HOUR, SAID OXIDATE BEINGCHARACTERIZED BY A NEUT. NO. TO SAP. NO. RATIO LESS THAN 0.25 AND ASAYBOLT VISCOSITY AT 210*F. GREATER THAN 4,000.